Sayang, please see your doctor or go to the clinic asap to check this out, at 10 weeks, any cramping and back pain needs proper checking to make sure everything's okay. I know it's scary, but better safe than sorry lah. A few of my mum friends had similar worries early on and their doctors put their minds at ease quickly, so go get it checked out, yeah? Jangan tunggu-tunggu. Wishing you all the best!